Factor by grouping x^3-4x^2+7x-28

(x - 4) (x^2 + 7)

Step-by-step explanation:

x^2 is a factor of the first two terms: x^3 - 4x^2 = x^2 (x - 4).

7 is a factor of the last two terms: 7 (x - 4).

Note how (x - 4) is a factor of the entire four-term expression given above.

Then: x^3-4x^2+7x-28 = (x - 4) (x^2 + 7)